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United States Patent |
5,304,667
|
Haeberle
,   et al.
|
April 19, 1994
|
Cyclosiloxanes containing mesogenic side groups
Abstract
The present invention relates to cyclic siloxanes which have at least one
group of formula (1) bonded to a silicon atom
--(CH.sub.2).sub.x --R"--[--L--A--].sub.y --(L).sub.z --T (1),
in which x is an integer having a value of at least 2, preferably having a
value of from 2 to 10, R" is a chemical bond or a divalent radical of the
formula --COO--, --OOC--, --CH.sub.2 --CH.sub.2 --, --CH.dbd.CH--,
--C.tbd.C--, --N.dbd.N--, --N.dbd.N, --N.dbd.CH--, --CH.dbd.N or
--Si(R).sub.2 --, where the radical R is identical or different and is an
optionally substituted hydrocarbon radical having from 1 to 18 carbon
atoms, L which is the same or different represents the 1,4-phenylene or
1,4-cyclohexylene radicals which are optionally 2-, 3-, 5- and/or
6-substituted by at least one radical Q, Q is the same or different
radical selected from hydrogen, fluorine or chlorine atoms or cyano,
methyl or trifluoromethyl groups, A is the same or different and
represents divalent radicals R" is a chemical bond or a divalent radical
of the formula --CH.sub.2 --O--, --O--CH.sub.2 --, y is an integer having
a value of from 0 to 10, preferably from 0 to 2, z is an integer having a
value of from 0 to 10, preferably from 0 to 2, with the proviso that the
sum y+z is at least 1, and T is a cholesteryl radical or a substituted or
unsubstituted hydrocarbon radical having from 1 to 18 carbon atoms, in
which the substituents are preferably selected from the group consisting
of halogen atoms, cyano groups, nitro groups, hydrocarbonoxy groups having
from 1 to 10 carbon atoms and mixtures thereof.
Inventors:
|
Haeberle; Norman (Munich, DE);
Haas; Wolfgang (Germering, DE);
Kreuzer; Franz-Heinrich (Martinsried, DE)
|
Assignee:
|
Consortium fur elektrochemische Industrie GmbH (Munich, DE)
|
Appl. No.:
|
038312 |
Filed:
|
March 29, 1993 |
Foreign Application Priority Data
Current U.S. Class: |
556/413; 556/415; 556/422; 556/425; 556/434; 556/438; 556/451; 556/460; 556/461 |
Intern'l Class: |
C07F 007/04; C07F 007/08; C07F 007/21 |
Field of Search: |
556/413,422,425,438,451,434,460,461,415
|
References Cited
U.S. Patent Documents
5221759 | Jun., 1993 | Haeberle et al. | 556/413.
|
Primary Examiner: Dees; Jose G.
Assistant Examiner: Conrad, III; Joseph M.
Parent Case Text
This application is a division of application Ser. No. 07/728,479, filed on
Jul. 11, 1991.
Claims
What is claimed is:
1. A cyclic siloxane which has at least one group of the formula
--(CH.sub.2).sub.x --R"--[--L--A--].sub.y --(L).sub.z--T ( 1)
bonded to a silicon atom in which x is an integer having a value of from 2
to 10, R" is selected from the group consisting of a chemical bond, and a
divalent radical selected from the group consisting of the formulas
--COO--, --OOC--, --CH.sub.2 --CH.sub.2, --CH.dbd.CH--, --C.tbd.C--,
--N.dbd.N--, --N.dbd.N(O)--, --CH.dbd.N--, --N.dbd.CH-- and --Si(R).sub.2
--, where the radical R is selected from the group consisting of a
hydrocarbon radical having from 1 to 18 carbon atoms and a substituted
hydrocarbon radical having from 1 to 18 carbon atoms, L is selected from
the group consisting of the 1,4-phenylene and the 1,4-cyclohexylene
radicals which may be optionally substituted at the 2-, 3-, 5- and/or 6
position by at least one radical Q, Q is selected from the group
consisting of hydrogen, fluorine, chlorine, cyano, methyl and
trifluoromethyl groups, A is a radical selected from the group consisting
of the divalent radicals R", radicals of the formula --CH.sub.2 --O-- and
--O--CH.sub.2 --, y is an integer having a value of from 0 to 10, z is an
integer having a value of from 0 to 10, with the proviso that the sum y+z
is at least 1, and T is a cholesteryl radical.
2. A process for preparing the cyclosiloxane of claim 1, which comprises
reacting a cyclic siloxane having at least one hydrogen atom bonded
directly to silicon with a compound selected from the group consisting of
formulas
H.sub.2 C.dbd.CH--(CH.sub.2).sub.(x-2)--R"--[--L--A--].sub.y
--(L).sub.z--T( 14),
and
##STR7##
in which R" is selected from the group consisting of a chemical bond, and
a divalent radical selected from the group consisting of the formulas
--COO--, --OOC--, --CH.sub.2 --CH.sub.2, --CH.dbd.CH--, --C.tbd.C--,
--N.dbd.N--, --N.dbd.N(O)--, --CH.dbd.N--, --N.dbd.CH-- and --Si(R).sub.2
--, where the radical R is selected from the group consisting of a
hydrocarbon radical having from 1 to 18 carbon atoms and a substituted
hydrocarbon radical having from 1 to 18 carbon atoms, L is selected from
the group consisting of the 1,4-phenylene and the 1,4-cyclohexylene
radicals which may be optionally substituted at the 2-, 3-, 5- and/or 6
position by at least one radical, Q, Q is selected from the group
consisting of hydrogen, fluorine, chlorine, cyano, methyl and
trifluoromethyl groups, A is a radical selected from the group consisting
of the divalent radicals R", radicals of the formula --CH.sub.2 --O-- and
-- O--CH.sub.2 --, y is an integer having a value of from 0 to 10, z is an
integer having a value of from 0 to 10, with the proviso that the sum y+z
is at least 1, and T is a cholesteryl radical and x is an integer having a
value of from 2 to 10.
3. A process for preparing the cyclosiloxane of claim 1, which comprises
reacting a cyclic siloxane having at least one alkenyl group of the
formula
--(CH.sub.2).sub.(x-2) --CH.dbd.CH.sub.2 ( 16),
bonded directly to silicon with a compound selected from the group
consisting of the formulas
##STR8##
in which R" is selected from the group consisting of a chemical bond, and
a divalent radical selected from the group consisting of the formulas
--COO--, --OOC--, --CH.sub.2 --CH.sub.2, --CH.dbd.CH--, --C.tbd.C--,
--N.dbd.N--, --N.dbd.N(O)--, --CH.dbd.N--, --N.dbd.CH-- and --Si(R).sub.2
--, where the radical R is selected from the group consisting of a
hydrocarbon radical having from 1 to 18 carbon atoms and a substituted
hydrocarbon radical having from 1 to 18 carbon atoms, L is selected from
the group consisting of the 1,4-phenylene and the 1,4-cyclohexylene
radicals which may be optionally substituted at the 2-, 3-, 5- and/or 6
position by at least one radical Q, Q is selected from the group
consisting of hydrogen, fluorine, chlorine, cyano, methyl and
trifluoromethyl groups, A is a radical selected from the group consisting
of the divalent radicals R", radicals of the formula --CH.sub.2 --O-- and
-- O--CH.sub.2 --, y is an integer having a value of from 0 to 10, z is an
integer having a value of from 0 to 10, with the proviso that the sum y+z
is at least 1, and T is a cholesteryl radical and x is an integer having a
value of from 2 to 10.
4. A cyclic siloxane which has at least one group of the formula
##STR9##
bonded to a silicon atom in which x is an integer having a value of from 2
to 10, R" is selected from the group consisting of a chemical bond, and a
divalent radical selected from the group consisting of the formulas
--COO--, --OOC--, --CH.sub.2 --CH.sub.2, --CH.dbd.CH--, --C.tbd.C--,
--N.dbd.N--, --N.dbd.N(O)--, --CH.dbd.N--, --N.dbd.CH-- and --Si(R).sub.2
--, where the radical R is selected from the group consisting of a
hydrocarbon radical having from 1 to 18 carbon atoms and a substituted
hydrocarbon radical having from 1 to 18 carbon atoms, Q is selected from
the group consisting of hydrogen, fluorine, chlorine, cyano, methyl and
trifluoromethyl groups, A is a radical selected from the group consisting
of the divalent radicals R", radicals of the formula --CH.sub.2 --O-- and
--O--CH.sub.2 --, y is an integer having a value of from 0 to 10, z is an
integer having a value of from 0 to 10, with the proviso that the sum y+z
is at least 1, and T is a cholesteryl radical.
5. An organocyclosiloxane of the formula
[RXSiO].sub.n ( 5)
in which X is selected from the group consisting of an R radical, a radical
of the formula
--(CH.sub.2).sub.x --R"--[--L--A--].sub.y --(L).sub.z--T ( 1)
and a radical of the formula
##STR10##
where R" is selected from the group consisting of a chemical bond, and a
divalent radical selected from the group consisting of the formulas
--COO--, --OOC--, --CH.sub.2 --CH.sub.2, --CH.dbd.CH--, --C.tbd.C--,
--N.dbd.N--, --N.dbd.N(O)--, --CH.dbd.N--, --N.dbd.CH-- and --Si(R).sub.2
--, where the radical R is selected from the group consisting of a
hydrocarbon radical having from 1 to 18 carbon atoms and a substituted
hydrocarbon radical having from 1 to 18 carbon atoms, L is selected from
the group consisting of the 1,4-phenylene and the 1,4-cyclohexylene
radicals which may be optionally substituted at the 2-, 3-, 5- and/or 6
position by at least one radical Q, Q is selected from the group
consisting of hydrogen, fluorine, chlorine, cyano, methyl and
trifluoromethyl groups, A is a radical selected from the group consisting
of the divalent radicals R", radicals of the formula --CH.sub.2 -- and
--O--CH.sub. 2 --, y is an integer having a value of from 0 to 10, z is an
integer having a value of from 0 to 10, with the proviso that the sum y+z
is at least 1, and T is a cholesteryl radical, x is an integer having a
value of from 2 to 10, and with a further proviso that the q radicals X
per molecule of formula (2) are radicals of formula (1), and the radical
R" has been replaced in the maximum of q-1 of these radicals of formula
(1) by a radical selected from the group consisting of the formulas --O--,
--CH.sub.2 --O--, and --O--CH.sub.2 --, q is an integer having a value of
from 1 to n, and n is an integer having a value of at least 3.
Description
The present invention relates to organocyclosiloxanes containing mesogenic
side chains, and more preferably organocyclosiloxanes containing mesogenic
side chains which are able to form liquid-crystalline phases.
BACKGROUND OF THE INVENTION
Liquid-crystalline compounds have been disclosed, inter alia, by B. D.
Demus, H. Demus and H. Zaschke (Flussige Kristalle in Tabellen [Liquid
Crystals in Tables], 1974; D. Demus and H. Zaschke, Flussige Kristalle in
Tabellen II [Liquid Crystals in Tables II], 1984, VEB-Verlag Leipzig).
Mesogenic groups are also described therein, i.e., groups whose presence
in a molecule may give the opportunity for the occurrence of
liquid-crystalline phases.
Organocyclosiloxanes containing mesogenic side groups are described in U.
S. Pat. No. 4,410,570 (published Oct. 18, 1983, F. H. Kreuzer et al.,
Consortium fur elektrochemische Industrie GmbH) in which the
liquid-crystalline organocyclosiloxanes have mesogenic groups bonded to
the respective silicon atom via a propyleneoxy group. They were prepared
by the addition reaction of allyloxy benzoates with a cyclosiloxane
containing Si-bonded hydrogen atoms. Siloxanes of this type tend to
eliminate propene, forming SiO-C bonds which are hydrolytically unstable.
It is an object of the present invention to provide substances containing
mesogenic side groups which have liquid-crystalline properties. Another
object of the present invention is to provide substances containing
mesogenic side groups having liquid-crystalline properties which can be
easily oriented. A further object of the present invention is to provide
substances containing mesogenic side groups which have liquid-crystalline
properties which are chemically stable.
SUMMARY OF THE INVENTION
The foregoing objects and others which will become apparent from the
following description are accomplished in accordance with this invention
generally speaking by providing cyclic siloxanes which have at least one
group of formula (1) bonded to a silicon atom
--(CH.sub.2).sub.x--R"--[--L--A--].sub.y --(L).sub.z--T ( 1),
in which x is an integer having a value of at least 2, preferably having a
value of from 2 to 10, R" is a chemical bond or a divalent radical of the
formula --COO--, --OOC--, --CH.dbd.CH--, --C.tbd.C-- or --Si(R).sub.2 --,
where the radical R is the same or different, and is a substituted or
unsubstituted hydrocarbon radical having from 1 to 18 carbon atoms, L is
the same or different and represents the 1,4-phenylene or
1,4-cyclohexylene radicals which are optionally 2-, 3-, 5- and/or
6-substituted by at least one radical Q, or are 2,5- or 3,6-pyridinediyl,
2,5-pyrimidindiyl, 2,5-pyridazinediyl, 2,5-triazinediyl,
3,6-tetrazinediyl, 2,5-dioxanediyl, 2,5-tetrahydrofurandiyl,
1,3,4-thiadiazole-2,5-diyl or 1,4-bicyclo[2.2.2]-octanediyl radicals, Q is
the same or different and represents hydrogen, fluorine or chlorine atoms
or cyano, methyl or trifluoromethyl groups, A is the same or different and
represents divalent radicals R" or radicals of the formula --CH.sub.2
--O--, --O--CH.sub.2 --, --CH.sub.2 --CH.sub.2 --, --N.dbd.N--,
--N.dbd.N(O)--, --CH.dbd.N-- or --N.dbd.CH--, y is an integer having a
value of from 0 to 10, preferably from 0 to 2, z is an integer having a
value of from 0 to 10, preferably from 0 to 2, with the proviso that the
sum y+z is at least 1, and T is a cholesteryl radical or a substituted or
unsubstituted hydrocarbon radical having from 1 to 18 carbon atoms, in
which the substituents are preferably selected from the group consisting
of halogen atoms, cyano groups, nitro groups, hydrocarbonoxy groups having
from 1 to 10 carbon atoms and mixtures thereof.
DESCRIPTION OF THE INVENTION
The term "at least one group of formula (1) bonded to a silicon atom" means
that the group of formula (1) is bonded directly to a silicon atom of the
cyclosiloxane.
The radical L is preferably a 1,4-phenylene radical.
Preferred radicals of formula (1) are those of formula (2):
##STR1##
x, y, z, R", Q, A and T are the same as above.
For purposes of the present invention, cyclic siloxanes mean monocyclic
cyclosiloxanes, preferably those represented by formula (5):
[RXSiO].sub.n (5)
in which X is the same or different radicals as defined for R or formula
(1), with the proviso that q radicals X per molecule are radicals of
formula (1), and the radical R" has been replaced in a maximum of q-1 of
these radicals of the formula (1) by a radical of the formula --O--,
--CH.sub.2 --O-- or --O--CH.sub.2 --, where q is an integer having a value
of from 1 to n and n is an integer having a value of at least 3, and R is
the same as above.
Preferably, all the radicals represented by X in formula (5) are radicals
of formula (1).
Examples of radicals represented by R are alkyl radicals, such as the
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,
n-pentyl, isopentyl, neopentyl and tert-pentyl radicals, hexyl radicals,
such as the n-hexyl radical, heptyl radicals, such as the n-heptyl
radical, octyl radicals, such as the n-octyl radical and isooctyl
radicals, such as the 2,2,4-trimethylpentyl radical, nonyl radicals, such
as the n-nonyl radical, decyl radicals, such as the n-decyl radical,
dodecyl radicals, such as the n-dodecyl radical and octadecyl radicals,
such as the n-octadecyl radical; cycloalkyl radicals, such as cyclopentyl,
cyclohexyl, cycloheptyl and methylcyclohexyl radicals; aryl radicals, such
as the phenyl, naphthyl, anthryl and phenanthryl radicals; alkaryl
radicals, such as 0-, m- and p-tolyl radicals, xylyl radicals and
ethylphenyl radicals; and aralkyl radicals, such as the benzyl radical and
the alpha- and .beta.-phenylethyl radicals.
Examples of substituted radicals R are cyanoalkyl radicals, such as the
.beta.-cyanoethyl radical, and halogenated hydrocarbon radicals, for
example haloalkyl radicals, such as the trifluoromethyl radical and the
3,3,3-trifluoro-n-propyl radical, and haloaryl radicals, such as the o-,
m- and p-chlorophenyl radicals.
In the above formulas (1), (2) and (5) and in the formulas below, R is
preferably the same or different C.sub.1 -- to C.sub.8 -alkyl, aryl,
aralkyl, alkaryl or cycloalkyl radical and in particular a methyl, ethyl,
n-propyl or phenyl radical. At least 80% of the radicals R, and more
preferably all the radicals R, are methyl radicals.
In formula (5), all the radicals X are preferably radicals of formula (1),
and in particular of formula (2).
In the formulas above and below, x is preferably an integer having a value
of from 3 to 12, preferably from 3 to 9, and more preferably from 3 to 6.
The radicals Q are preferably the same or different radicals, namely
hydrogen, chlorine or fluorine atoms or cyano radicals, and more
preferably hydrogen atoms.
Preferred radicals T are cholesteryl radicals, and radicals of the formulas
##STR2##
in which Z is the same or different radicals, namely hydrogen atoms,
halogen atoms or cyano, nitro, C.sub.1 - to C.sub.6 -alkyl or C.sub.1 - to
C.sub.6 -alkoxy radicals.
Particularly preferred radicals of formula (1) or (2) and particularly
preferred radicals X are those of formula (12):
##STR3##
in which a is the same or different integer having a value of from 2 to 6,
R* is the same or different divalent radical, namely a single chemical
bond or a radical of the formula --OOC-- or --Si(CH.sub.3).sub.2 --, M is
the same or different radical of the formula --OOC--, --COO--,
--N.dbd.CH-- or --CH.dbd.N--, and G is a cholesteryl radical or a phenyl
or biphenyl radical which is optionally 4-substituted by a halogen atom, a
cyano radical, a C.sub.1 - to C.sub.4 -alkyl group or an alkoxy group.
Particularly preferred cyclosiloxanes of this invention are
organocyclosiloxanes of formula (13):
##STR4##
in which b is an integer having a value of from 3 to 6, and a, R*, M and G
are the same as above, with the proviso that, for b-1 radicals of formula
(12) in formula (13), the radical R* may also be a radical of the formula
--O--.
If the structure permits, the compounds claimed also include the
diastereomers and optical isomers thereof, i.e., in particular, the
individual enantiomers and mixtures thereof, for example the corresponding
racemates.
PROCESSES
Process 1
The cyclosiloxanes of this invention containing mesogenic side groups can
be prepared by reacting a cyclic siloxane having at least one hydrogen
atom bonded directly to silicon with a compound of formula (14) or (15):
##STR5##
preferably in the presence of at least one platinum-group metal and/or a
compound thereof, where, in the above formulas (14) and (15), R", L, A, T,
x, y, z and Q are the same as above.
The platinum catalyst is preferably employed in amounts of from 0.02 to 50
mol percent, based on the elemental platinum and based on the number of
moles of the particular reaction component, i.e., of the compound(s) of
formula (14) or (15) or of the cyclic siloxanes having at least one
hydrogen atom bonded directly to silicon, which is present in a
substoichiometric amount or in a stoichiometric amount.
The reaction is preferably carried out at temperatures of from 0.degree. C.
to 150.degree. C., preferably at pressures of from 0.05 MPa to 2.0 MPa.
If the cyclosiloxane, i.e., preferably that of formula (19) or (20), or the
compound of the formula (14) or (15) is very inert, it is also possible to
use elevated temperatures, higher pressures and to employ more platinum
catalyst.
The reaction is preferably carried out in a solvent, and more preferably an
aprotic solvent; solvents or solvent mixtures having a boiling point or
boiling range up to about 160.degree. C., preferably up to about
120.degree. C., at 0.1 MPa (abs.). Examples of solvents are esters, such
as methyl acetate, ethyl acetate, n- and isopropyl acetate, n-, sec- and
t-butyl acetate, ethyl formate and diethyl carbonate; ethers, such as
dioxane, tetrahydrofuran, diethyl ether, di-n-propyl ether, diisopropyl
ether, di-n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, diethylene glycol dimethyl ether and anisole; chlorinated
hydrocarbons, such as dichloromethane, trichloromethane,
tetrachloromethane, 1,2-dichloroethane, trichloroethylene,
tetrachloroethylene and chlorobenzene; hydrocarbons, such as pentane,
n-hexane, hexane isomeric mixtures, cyclohexane, heptane, octane, naphtha,
petroleum ether, benzene, toluene and xylenes; ketones, such as acetone,
methyl ethyl ketone and methyl isobutyl ketone; or mixtures of these
solvents.
The term solvent does not mean that all the reaction components must be
soluble therein. The reaction can also be carried out in a suspension or
emulsion of one or more reactants. The reaction can also be carried out in
a solvent mixture having a miscibility gap, at least one reactant being
soluble in each of the phases of the mixture.
The cyclic siloxane containing at least one hydrogen atom bonded directly
to silicon, preferably a cyclic siloxane of formula (19) or (20), is
preferably employed in the process of this invention in a molar ratio,
compared to the compound of formula (14) or (15), of from 1:2 to 2:1, in
particular from 1:1.1 to 1.1:1.
Preparation of Compounds of Formula (14) and (15):
Processes for the preparation of starting compounds of the formulas (14)
and (15) and of intermediates thereof are described in DE-A 3 935 638. For
example, the alkenyl radical can be introduced by reacting the appropriate
alkenyl halides with appropriate organometallic benzene derivatives, in
particular the Grignard compounds and organolithium compounds. Preferred
examples of such benzene derivatives are 4-halobenzenemagnesium halides.
The reaction of an alkenyl halide with a benzene derivative is preferably
carried out in an inert solvent (mixture), for example diethyl ether,
methyl-t-butyl ether, tetrahydrofuran, 1,4-dioxane, hydrocarbons and
mixtures thereof, such as benzene, toluene, xylenes, hexane isomer
mixtures or petroleum ether. The reaction is preferably carried out at
temperatures of from -100.degree. C. to +110.degree. C., in particular at
pressures of from 0.09 to 0.11 MPa (abs.). Under certain circumstances,
the reaction may be accelerated by ultrasound.
4-(.omega.-Alkenyl)-1-halobenzenes prepared in this manner can be reacted,
inter alia, a second time with magnesium to give the corresponding
organomagnesium halides and subsequently with CO.sub.2 to give
4-(.omega.-alkenyl benzoic acids and finally to give the corresponding
cholesteryl or optionally substituted phenyl esters (A=--COO-- in formula
(14) or (15)). A list of 4-(.omega.-alkenyl) benozoic acid esters which
can be prepared in this manner is given in Table 1.
4-.omega.-Alkenylphenol derivatives can be obtained by reaction
4-.omega.-alkenylmagnesium halides with 4-halophenols which are protected
on the hydroxyl group, if necessary with a dilithium tetrachlorocuprate
catalyst. The phenols obtained in this manner can be esterified using
appropriate acids or acid derivatives (A=--OOC-- in formula (14) or (15)).
Examples of phenol esters which can be prepared correspondingly are given
in Table 2.
Reaction of 4-(.omega.-alkenyl)phenylmagnesium halides (preparable as
explained above) with N,N-dimethylformamide gives 4-(.omega.-alkenyl)
benzaldehydes, which in turn react with primary amines, for example with
the commercially available 4-alkylanilines, to give the corresponding
azomethines (Schiff bases) (A=--CH.dbd.N-- in formula (14) or (15)). The
compound, n-[4-(3-butenylphenyl) benzylidene]-4-butylphenylimine (boiling
point at 2 Pa: 170.degree. C.) was prepared in this manner.
Reaction of the 4-(.omega.-alkenyl)benzaldehydes which can be prepared by
the above process with suitable derivatives, for example alkanephosphonic
acid esters (Wittig-Horner reaction) give
4-(.omega.-alkenyl)phenylethylenediyl derivatives (A=--CH.dbd.CH-- in
formula (14) or (15)).
According to EP-A-168 683, Example 26, 1-(.omega.-alkenyl)-4-nitrobenzene
can be reduced to give 4,4'-di(.omega.-alkenyl)azoxybenzenes, for example
by means of magnesium turnings in methanol as solvent (A=--N.dbd.N(O)-- in
formula (14) or (15)). This compound can in turn be reduced in a known
manner to give the corresponding azobenzene (A=--N.dbd.N-- in formula (14)
or (15)), for example by means of zinc and sodium hydroxide solution.
All the processes for preparing these and other compounds of formulas (14)
and (15) and for the starting materials under process 2 are known and are
described, for example, in Houben-Weyl, Methoden der organischen Chemie
[Methods of Organic Chemistry], Georg Thieme Verlag, Stuttgart and New
York.
Some of the cyclic siloxanes which have at least one hydrogen atom bonded
directly to silicon and are employed in process 1 are commercially
available from Petrarch Systems (represented by ABCR GmbH & Co. KG, D-7500
Karlsruhe). Their preparation is described, inter alia, in U.S. Pat. No.
2,389,806 and by R. O. Sauer et al. (Journal of the American Chemical
Society 68, 962 (1946)). A review of siloxanes and their preparation is
given by W. Noll in "Chemistry and Technology of Silicones", Academic
Press Inc., Orlando, 1968.
Process 2
The cyclosiloxanes of this invention containing mesogenic side groups can
be prepared by reacting a cyclic siloxane containing at least one alkenyl
group of the formula
--(CH.sub.2).sub.(x-2)--CH.dbd.CH.sub.2 (16),
which is bonded directly to silicon with a compound of formula (17) or (18)
##STR6##
preferably in the presence of at least one platinum-group metal and/or
compounds thereof, where, in the above formulas (16), (17) and (18), L, A,
T, x, y, z and Q are the same as above.
In the formulas (17) and (18), R" is a group of the formula --Si(R).sub.2
--, and more preferably of the formula --Si(CH.sub.3).sub.2 --, where R is
the same as above.
Conditions for process 1 in regard to additional components in the reaction
mixture, such as a platinum catalyst and a solvent, or the mixing ratios
of the components and or the pressure and temperature apply as well to
process 2.
In formula (16) above, x preferably has the value 2 or 3, and more
preferably 2. Preferred cyclic siloxanes containing at least one alkenyl
group of formula (16) bonded directly to silicon are thus cyclic siloxanes
containing vinyl and/or allyl groups, and in particular those containing
vinyl groups.
Cyclosiloxanes containing methyl and vinyl groups can be prepared, for
example, by hydrolyzing vinylmethyldichlorosilane or cohydrolyzing this
silane using dimethyldichlorosilane in a water/tetrahydrofuran mixture and
subsequently subjecting the product to fractional distillation.
The preparation of 4-dimethylsilylchlorobenzene, the corresponding Grignard
compound and 4-dimethylsilylbenzoic acid, prepared therefrom by reaction
with CO.sub.2, or the acid chloride is described in U.S. Pat. No.
4,914,221. The preparation involves reaction of 1,4-dichlorobenzene with
magnesium to give 4-chloro benzenemagnesium chloride and reaction thereof
with trichlorosilane.
Compounds of formulas (17) and (18) can be prepared from
4-dimethylsilyl-1-chlorobenzene analogously to that stated above for
process 1 under the heading "Preparation of compounds of formulas (14) and
(15):".
In all the processes described above, each compound present in the reaction
mixture can be employed individually or as a mixture. Thus, for example,
it is possible to employ in each case a reactant of one of the above
mentioned formulas or a reactant which carries a radical of one of the
above mentioned formulas, but it is also possible to employ a mixture of
at least two such reactants. A solvent can be used if desired, and a
catalyst can be used if necessary, but it is also possible to use a
solvent mixture and/or a catalyst mixture.
The cyclic siloxanes of this invention or those that are capable of being
prepared according to this invention and containing mesogenic side chains
can be used in display devices, particularly in display devices produced
using smectic liquid crystals or liquid crystal mixtures. These can use
the pure compounds of this invention, mixtures thereof and in particular
mixtures of the cyclic siloxanes of this invention with (other) liquid
crystals. The compounds of this invention are suitable for the preparation
of nematic, cholesteric and smectic mixtures, in particular mixtures which
are able to form a smectic C phase. However, they can also be used as
additives for nematic, smectic or cholesteric phases. With the aid of the
cyclic siloxanes of this invention, the liquid-crystalline base mixtures
can be prepared and the properties of base mixtures which have already
been prepared, such as, for example, the optical anisotropy, the
electrical anisotropy, the spontaneous polarization, the viscosity, the
tilt angle, the pitch and the phase behavior, can be favorably modified.
The proportion of cyclic siloxanes of this invention containing mesogenic
side groups in the liquid-crystal mixtures can be varied within broad
limits depending on the application. For example, the proportion can be
from 1 percent by weight up to 100 percent by weight.
In the table and examples below, unless otherwise specified,
(a) all amounts are by weight;
(b) all pressures are 0.10 MPa (abs.); and
(c) all temperatures are at 20.degree. C.
The phase descriptions are abbreviated as follows:
(d) the numbers denote transition temperatures, measured in .degree.C.;
(e) the phase types are characterized as follows:
I: isotropic phase,
N: nematic phase,
ChcL: cholesteric phase,
S.sub.A : smectic A phase,
S.sub.C : smectic C phase,
S.sub.C* : chiral smectic C phase,
S.sub.B : smectic B phase,
S: smectic state of undetermined type,
C: crystalline,
T.sub.G : glass state.
(f) phase descriptions in parentheses indicate supercoolable phases.
TABLE 1
Starting materials of formula (14) or (15):
4-(.omega.-alkenyl)benzoic acid esters
cholesteryl 4-allylbenzoate C 139 Chol 203 I
cholesteryl 4-(3-butenyl)benzoate C 130 Chol 217
cholesteryl 4-(4-pentenyl)benzoate C 118 S.sub.A 125 Chol 194 I
cholesteryl 4-(5-hexenyl)benzoate C 108 S.sub.A 128 Chol 197 I
4-methoxyphenyl 4-allylbenzoate C 85 I
4-methoxyphenyl 4-(3-butenyl)benzoate C 56 (N 40) I
4-methoxyphenyl 4-(4-pentenyl)benzoate C 49 I
4-methoxyphenyl 4-(5-hexenyl)benzoate C 59 I
4-cyanophenyl 4-allylbenzoate C 110 I
4-cyanophenyl 4-(3-butenyl)benzoate C 92 I
4-cyanophenyl 4-(4-pentenyl)benzoate C 44 I
4-cyanophenyl 4-(5-hexenyl)benzoate C 63 I
4-chlorophenyl 4-allylbenzoate C 54-56 I
4-chlorophenyl 4-(3-butenyl)benzoate C 50-51 I
4-chlorophenyl 4-(4-pentenyl)benzoate C 47 I
4-chlorophenyl 4-(5-hexenyl)benzoate C 54 I
4-biphenylyl 4-allylbenzoate C 146 I
4-biphenylyl 4-(3-butenyl)benzoate C 108 I
4-propylphenyl 4-(3-butenyl)benzoate C 24 I
4-biphenylyl 4-(4-pentenyl)benzoate C 127-128 I
4-biphenylyl 4-(5-hexenyl)benzoate C 114-118 I
4-octyloxyphenyl 4-(3-butenyl)benzoate C 42 N 61 I
4-cyanobiphenylyl 4-(3-butenyl)benzoate C 123 N 261 I
5-hexenyl 4-((4-chlorophenyl)carbonyloxyphenyl)benzoate C 52 I
5-hexenyl 4-((4-biphenylyl)carbonyloxyphenyl)benzoate C 98 I
4-trimethylsilybutylphenyl 4-(3-butenyl)benzoate b.p.
203.degree.-204.degree. C. at 0.2 mbar.
TABLE 2
Starting materials of the formula (14) or (15):
4-(.omega.-alkenyl)phenyl esters
4-(3-butenyl)phenyl 4-chlorobenzoate C 67 I
4-(3-butenyl)phenyl 4-biphenylylcarboxylate C 97 N 107 I
4-(3-butenyl)phenyl 4-methoxybenzoate C 70 I
4-allylphenyl 4-biphenylylcarboxylate C 114 I
4-allylphenyl 4-methoxybenzoate C 63 I
TABLE 3
Cyclic siloxanes of this invention prepared by process 1
cyclopentasiloxane, pentamethyl-penta(4-cholesteryloxycarbonyl)
phenylpropyl)- T.sub.G 82 S.sub.A 246 I
cyclopentasiloxane, pentamethyl-penta(4-cholesteryloxycarbonyl)
phenylbutyl)-, T.sub.G 65 S.sub.A 240 I
cyclopentasiloxane, pentamethyl-penta(4-cholesteryloxycarbonyl)
phenylpentyl)-, T.sub.G 51 S.sub.A 255 I
cyclopentasiloxane, pentamethyl-penta(4-cholesteryloxycarbonyl)
phenylhexyl)-, T.sub.G 40 S.sub.A 248 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-methoxyphenyloxycarbonylphenyl)butyl)-, T.sub.G 10
N 5
cyclopentasiloxane,
pentamethyl-penta(4-(4-cyanophenyloxycarbonylphenyl)propyl)-, T.sub.G 36 N
84 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-cyanophenyloxycarbonylphenyl)butyl)-, C 84 N 100 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-cyanophenyloxycarbonylphenyl)hexyl)-, C 54 S.sub.A
105 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-chlorophenyloxycarbonylphenyl)butyl)-, T.sub.G 50
S.sub.E 94 S.sub.A 115 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-chlorophenyloxycarbonylphenyl)hexyl)-. T.sub.G 2
S.sub.E 33 S.sub.A 120 I
cyclopentasiloxane, pentamethyl-penta(4-biphenylyloxycarbonylphenylbutyl)-,
C 145 (T.sub.G 93 N 140) I
cyclopentasiloxane,
pentamethyl-penta(4-biphenylyloxycarbonylphenylpentyl)-, C 120 N 142 I
cyclopentasiloxane, pentamethyl-penta(4-(4-biphenylylcarbonyloxy)
phenylbutyl)-, T.sub.G 46 S.sub.x 117 S.sub.C 133 N 146 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-methoxyphenylcarbonyloxy)phenylbutyl)-, T.sub.G -3
N 65 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-biphenylylcarbonyloxy)phenylpropyl)-, T.sub.G 30
S.sub.B 57 S.sub.A 127 N 136 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-methoxyphenylcarbonyloxy)phenylpropyl)-, T.sub.G 7
N
cyclopentasiloxane,
pentamethyl-penta(4-(4-cyanobiphenylyloxycarbonylphenyl)butyl)-, T.sub.G
48 S.sub.B 112 S.sub.A 144 N>300 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-cyanobiphenylyloxycarbonylphenyl)hexyl)-, T.sub.G
34 S.sub.B 112 S.sub.A >300 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-chlorophenylcarbonyloxy)phenylcarbonyloxyhexyl)-,
T.sub.G 5 S.sub.E 43 S.sub.B 83-90 S.sub.A 96-114 I
cyclopentasiloxane,
pentamethyl-penta(4-(4-biphenylylcarbonyloxy)phenylcarbonyloxyhexyl)-,
T.sub.G 16 S.sub.A, C 64 S.sub.A 176-192 I
cyclopentasiloxane, pentamethyl-(4-(cholesteryloxycarbonyl)phenyloxyhexyl)
.sub.1.25 -[4-biphenylyloxycarbonyl)phenyloxyhexyl].sub.1.25
(4-cholesteryloxycarbonyl)phenylbutyl).sub.1.25
-(4-(biphenylyloxycarbonyl)phenylbutyl).sub.1.25 .multidot.T.sub.G 41
S.sub.C 63-66 S.sub.A 173-177 Chol 201 I
cyclopentasiloxane,
pentamethyl-(4-cholesteryloxycarbonyl)phenylbutyl).sub.2.5
-(4-(biphenylyloxycarbonyl)phenylbutyl).sub.2.5 T.sub.G 44 S.sub.A 184
Chol 207 I
cyclopentasiloxane,
pentamethyl-(4-(cholesteryloxycarbonyl)phenylpropyl).sub.2.5
-(4-(4-methoxyphenyloxycarbonyl)-phenylbutyl).sub.2.5 T.sub.G 38 Chol 176
I
cyclopentasiloxane, pentamethyl-(4-(cholesteryloxycarbonyl)
phenylbutyl.sub.2.5 -(4-(4-methoxyphenyloxycarbonyl)-phenylpropyl).sub.2.5
T.sub.G 37 Chol 170 I absorption maximum at 396 nm
cyclopentasiloxane, pentamethyl-(4-(cholesteryloxycarbonyl)
phenylpropyl).sub.3 -(4-(4-methoxyphenyloxycarbonyl)-phenylbutyl).sub.2
absorption maximum at 436 nm. T.sub.G 47 Chol 196 I
cyclopentasiloxane, pentamethyl-(4-(cholesteryloxycarbonyl)
phenylpropyl).sub.1.75
-(4(4-methoxyphenyloxycarbonyl)-phenylbutyl).sub.3.25 absorption maximum
at 460 nm. T.sub.G 26 Chol 141 I
cyclopentasiloxane, pentamethyl-(4-(cholesteryloxycarbonyl)
phenylpropyl).sub.0.75
-(4-(4-methoxyphenyloxycarbonyl)-phenylbutyl).sub.4.25 absorption maximum
at 640 nm. T.sub.G 15 Chol 84 I
cyclotetrasiloxane, tetramethyl-(4-cholesteryloxycarbonyl)
phenylpropyl).sub.2 -(4-(4-methoxyphenyloxycarbonyl)-phenylbutyl).sub.2
T.sub.G 36 Chol 162-163 I absorption maximum at 460 nm
cyclohexasiloxane,
hexa-[(4-butylphenyl)iminomethyl-4-phenylbutyl]hexamethyl C 75-103 i.
EXAMPLE 1
(a) Preparation of 4-(.omega.-alkenyl)-1-halobenzenes
A solution containing 294 g (2 mol) of 1,4-dichlorobenzene in 500 ml of
anhydrous tetrahydrofuran was added dropwise over a period of about 110
minutes under nitrogen at 80.degree. C. to a stirred suspension containing
48.6 g (2.0 mol) of magnesium turnings. The mixture was subsequently
heated for 2 hours at 80.degree.-84.degree. C., then decanted from the
excess magnesium, and the resultant solution of the Grignard compound was
added dropwise over a period of 30 minutes at 80.degree. C. to a stirred
solution containing 194 g (1.8 mol) of 6-bromo-1-hexene (Fluka GmbH, 7910
Neu-Ulm) in 200 ml of tetrahydrofuran. The mixture was then stirred for 4
hours at 80.degree. C. and then poured onto ice. After acidification with
hydrochlcric acid, the mixture was extracted three times with a 1:1
mixture of diethyl ether/methyl tert-butyl ether, and the ether fractions
were stirred thoroughly with activated charcoal and dried over sodium
sulfate. The filtrate was evaporated, and the residue was fractionated. At
a pressure of 13 hPa and a temperature of 116.degree.-118.degree. C., 156
g (corresponding to a yield of 40% of theory) of
4-(5-hexenyl)-1-chlorobenzene were obtained. 4-(8-Nonenyl)-1-chlorobenzene
(b.p. 87.degree. C. at 0.3 hPa), for example, can also be prepared in the
same way.
(b) Preparation of 4-(.omega.-alkenyl)benzoic acids
An initial amount of a total of 137 g (0.7 mol) of
4-(5-hexenyl)-1-chlorobenzene in 170 ml of tetrahydrofuran was added at
80.degree. C. to 19.5 g (0.8 mol) of magnesium turnings. After the
reaction had commenced, the remainder of the solution was added dropwise
over a period of 2.5 hours with stirring at 80.degree.-82.degree. C., and
the mixture was subsequently stirred for 4 hours at 80.degree.-84.degree.
C.
About 150 ml of tetrahydrofuran were saturated at 10.degree. C. with
CO.sub.2, and the Grignard solution decanted from the excess magnesium,
was then added dropwise with stirring at 5.degree.-15.degree. C., and
additional CO.sub.2 was passed into the flask. When the addition was
complete, a post-reaction time of 2 hours was allowed, and the mixture was
poured onto ice and acidified using hydrochloric acid, and the resultant
emulsion was extracted three times with methyl tert-butyl ether. Washing,
drying and evaporation of the organic phase gave 73 g (47.6% of theory) of
4-(5-hexenyl)benzoic acid (recrystallization from petroleum ether gives a
product having a melting range of 79.degree.-82.degree. C.).
Reaction of this acid with thionyl chloride in toluene using
dimethylformamide as catalyst gave 65.6% of theory of the corresponding
acid chloride (b.p. 118.degree. C. at 13 mbar). Reaction of this acid
chloride with 4-hydroxybiphenyl using triethylamine as acid scavenger gave
a 61.8% yield of 4-biphenyl 4-(5-hexenyl)-benzoate, which has a melting
range of 114.degree.-118.degree. C.
(c) Preparation of the cyclopentasiloxane adduct
About 5.7 g (15.3 mmol) of this ester, dissolved in 35 g of toluene, 0.9 g
(0.3 mmol) of pentamethylcyclopentasiloxane (ABCR GmbH, 7500 Karlsruhe)
and 0.8 ml of a 0.5% solution of dicyclopentadienylplatinum dichloride in
dichloromethane were refluxed together for 60 minutes. The Pt catalyst was
removed from the resultant solution by purification on a short silica gel
column. The target product was precipitated using 200 ml of ethanol,
filtered off and redissolved in pure toluene. Reprecipitation, filtration
and drying gave 3.1 g (47% of theory) of
pentamethyl-penta(4-biphenylyloxycarbonylphenylhexyl)cyclopentasiloxane,
which has the following phase behavior: S.sub.I 117 S.sub.C 133 N 146-147
I.
EXAMPLE 2
Preparation of
pentamethyl-penta-(4-(4-biphenylylcarbonyloxy)phenylbutyl)cyclopentasiloxa
ne
(a) 4-Methoxymethoxy-1-bromobenzene was prepared from formaldehyde dimethyl
acetal and 4-bromophenol by the method of Y. P. Yardley and H. Fletcher,
Synthesis 1976. p. 244. The boiling point of this derivative is
54.degree.-56.degree. C. at 0.1 hPa, and the yield is 49% of theory.
About 4.6 g (0.19 mol) of magnesium turnings were moistened under nitrogen
with absolute tetrahydrofuran, warmed to 60.degree. C. and treated with a
few drops of ethyl iodide as initiator. After the reaction had commenced,
the remainder of a total of 35 g (0.16 mol) of the bromine compound,
dissolved in 150 ml of tetrahydrofuran, was metered in at such a rate that
the mixture continued to boil, and the mixture was subsequently refluxed
for an additional 2.5 hours. A catalytic amount of a solution of dilithium
tetrachlorocuprate (containing 25% of dilithium tetrabromocuprate) and a
solution of 16.2 ml (0.16 mol) of 4-bromo-1-butene in 200 ml of THF were
then added. The mixture was refluxed for 16 hours, then cooled and poured
onto ice. After acidification and phase separation, the aqueous phase was
extracted twice with 400 ml of methyl tertbutyl ether. The organic phases
were dried and evaporated. The residue was fractionated under reduced
pressure, giving 16.5 g (corresponding to 53.6% of theory) of
4-(methoxymethoxy)-1-(3-butenyl)benzene with a boiling point of
118.degree.-120.degree. C. and a pressure of 15 hPa.
Warming of this derivative at 95.degree.-100.degree. C. (40 hours) with 2N
acetic acid liberated 20.8 g of 4-(3-butenyl)phenol (42.1% of theory) at a
pressure of 16 hPa and 130.degree.-140.degree. C.
(b) Esterification of this phenol derivative using commercial
biphenyl-4-carbonyl chloride (Janssen Chimica, 4057 Bruggen 2) in toluene
as solvent and with triethylamine as acid scavenger gave
4-(3-butenyl)phenyl-4-biphenylylcarboxylate in the form of colorless
leaves in a yield of 76.2% of theory. The ester has the following phase
behavior: C 97 N 107 I.
(c) The addition reaction of the resultant ester with
pentamethylcyclopentasiloxane in accordance with the procedure of Example
1 (c) gave the desired product in a virtually quantitative yield. The
following phases were observed: T.sub.G 46 S.sub.x 125 S.sub.B 137 S.sub.A
170 I.
EXAMPLE 3
Preparation of
tetramethyl-di(4-(cholesteryloxycarbonyl)-phenylpropyl)-di(4-(4-methoxyphe
nyloxycarbonyl)phenylbutyl)cyclotetrasiloxane.
About 4-Methoxyphenyl 4-(3-butenyl)benzoate (m.p. 54.degree. C.) and
cholesteryl 4-allylbenzoate (C 139 Chol 203 I) were prepared analogously
to Examples 1(a) and (b) respectively, and added in equimolar amounts, as
described in Example 1(c), to tetramethylcyclotetrasiloxane. After
purification, the resultant product had the following behavior: glass
transition temperature (T.sub.G) 36 Chol 162-163 I. The absorption
spectrum had a maximum at 460 nm.
EXAMPLE 4
Preparation of
hexa[(4-butylphenyl)iminomethyl-4-phenylbutyl]hexamethylcyclohexasiloxane.
(a) First, 4-(3-butenyl)-1-bromobenzene was prepared by the method of P. E.
Peterson et al., J. Org. Chem. 33, 972 (1968). About 133 g (0.63 mol) of
this product were dissolved in 110 ml of tetrahydrofuran, and the mixture
was added dropwise over a period of about 3 hours at 75.degree.-95.degree.
C. with stirring to 17 g (0.7 mol) of magnesium turnings. The mixture was
then cooled, the Grignard solution was decanted off from the magnesium and
added dropwise over a period of about 2 hours at 5.degree.-10.degree. C.
to a solution containing 57.7 g (0.8 mol) of dimethylformamide in
35.degree. C. for an additional hour. After the mixture had been cooled,
hydrolyzed and worked up, the organic phase was fractionated in a short
column, giving 56.2 g of 4-(3-butenyl)benzaldehyde (55.7% yield) at a
pressure of 16 mbar and a boiling point of 124.degree. C.
(b) About 26.0 g (0.1 mol) of this aldehyde and 14.9 g (0.1 mol) of
commercially available 4-butylaniline were dissolved in 200 ml of toluene,
0.3 g of 4-toluenesulfonic acid was added as catalyst, and the mixture was
refluxed for 90 minutes. The water formed was removed azeotropically via a
separator. The reaction residue was fractionated. The desired imine had a
boiling point of 170.degree. C. at 0.02 mbar. About 19.1 g of substance
(65.6% of theory) were obtained after recrystallization from ethanol.
(c) About 1.6 g (4.5 mmol) of hexamethylcyclohexasiloxane and 8.7 g (30
mmol) of the imine from (b) were reacted (60 minutes) analogously to
Example 1(c) at 50.degree.-90.degree. C. in 10 ml of toluene with the aid
of 0.4 ml of a 0.5% platinum catalyst solution. Reprecipitation twice from
ethanol gave 6.5 g (68% of theory) of the desired adduct, which has the
following phase behavior: C, 56 S.sub.A 88-103 I.
EXAMPLE 5
Comparison Example
About 4-propylphenyl 4-allyloxybenzoate (melting point
53.degree.-55.degree. C.) and 4-propylphenyl 4-(3-butenyl)benzoate
(melting point 24.degree. C.) were reacted under identical reaction
conditions with the pentamethylcyclopentasiloxane described in Example
1(c). In the case of both substances, the solvent was first removed and
.sup.1 H-NMR spectra were recorded for the unpurified residues.
The adduct of 4-(3-butenyl)benzoate exhibits the expected signals with
clear resolution; the integrals of the individual signals correspond to
one another.
The adduct of 4-allylbenzoate exhibits individual signals with multiple
splitting (caused by by-products). The heights of the integrals of the
individual signals differ from one another by up to 20%. A comparison of
the high-pressure gel permeation chromatograms shows that the
4-allyloxybenzoate adduct contains more than twice the contamination
caused by by-products as the 4-(3-butenyl)benzoate adduct (no oxygen in
the spacer).
Both crude products were dissolved in toluene and purified by
chromatography in equal length columns containing silica gel. This showed
the 4-(3-butenyl)benzoate adduct to contain 3.2% of impurities, while, by
contrast, the 4-allyloxybenzoate adduct contained 28.7% of impurities. The
increased proportion of impurities compared with the crude product is
caused by the silica gel used for chromatography, whose surface water is
sufficient, in spite of the aprotic eluent, to cause considerably
hydrolysis.
EXAMPLE 6
Comparison Example
A 1:1 mixed adduct, prepared as described in EP 60 335, of cholesteryl
4-(propen-2-oxy)benzoate and 4'-phenylphenyl
4-(propen-2-oxy)phenylbenzoate with pentamethylcyclopentasiloxane has a
broad absorption region (52 nm) at 632-580 nm whose broadening is caused
by by-products. A comparable 1:1 adduct according to the invention of
cholesteryl 4-(3-butenyl)benzoate and 4-methoxyphenyl
4-(2-propen-1-yl)benzoate with pentamethylcyclopentasiloxane has a
significantly narrower absorption region (25 nm) at 380-405 nm.
EXAMPLE 7
Preparation by Process 2
About 0.65 g (1.89 mmol) of
1,2,3,4-tetravinyl-1,2,3,4-tetramethylcyclotetrasiloxane, 2.50 g (7.53
mmol) of 4-biphenyl 4-dimethylsilylbenzoate and 80 mg (2 .mu.mol of Pt) of
1% dicyclopentadienylplatinum dichloride solution in dichloromethane were
refluxed for 30 minutes in 5 ml of dry toluene. The reaction product was
precipitated from the toluene using methanol and purified by
chromatography on silica gel, giving a 78% yield of
1,2,3,4-tetrakis(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)ethy
l)-1,2,3,4-tetramethylcyclotetrasiloxane, phases: C 82-85 i.
The following were prepared analogously:
1,2,3-tris(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-1,2,3-trimethylcyclotrisiloxane, phases: G 63 S.sub.C 141-157
i;1,2,3,4-tetrakis(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)e
thyl)-1,2,3,4-tetramethylcyclotetrasiloxane, phases: T.sub.G 67 S.sub.C 164
I;
1,2,3-tris(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-1,2,3-trimethylcyclotrisiloxane, phases: C 88 (G 46) I;
1-(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)ethyl)
-2,3-bis(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-1,2,3-trimethylcyclotrisiloxane, phases: T.sub.G 41 s.sub.c 86 I;
1,2-bis(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-3-(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-1,2,3-trimethylcyclotrisiloxane, phases: T.sub.G 47 s.sub.c 126 I;
1,2,3,4,5-pentakis(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)et
hyl)-1,2,3,4,5-pentamethylcyclopentasiloxane, phases: T.sub.G 80 s.sub.c
179-196 I;
1,2,3-tris(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-4-(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-1,2,3,4-tetramethylcyclotetrasiloxane, phases: T.sub.G 61 s.sub.A
146-153 I;
1,2-bis(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)
ethyl(-3,4-bis(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)ethyl-
1,2,3,4-tetramethylcyclotetrasiloxane, phases: T.sub.G 50 s 105-120 I;
1-(2-cholesteryloxycarbonylphenylene-4-dimethylsilylene)-ethyl)
-2,3,4-tris(2-(4-biphenyloxycarbonylphenylene-4-dimethylsilylene)
ethyl-1,2,3,4-tetramethylcyclotetrasiloxane, phases: T.sub.G 39 s 84-88 I;
1,2-bis(2-(cholesteryloxycarbonylphenylene-4-dimethylsilylene)
ethyl)-3,4-bis(2-(4-methoxyphenyloxycarbonylphenylene
-4-dimethylsilylene)ethyl)-1,2,3,4-tetramethylcyclotetrasiloxane, phases:
T.sub.G 40 s 58 I;
1,2,3,4-tetrakis(2-(4-cyanophenyleneoxycarbonylphenylene-4-dimethylsilylene
)ethyl)-1,2,3,4-tetramethylcyclotetrasiloxane, phases: T.sub.G 37 I;
1,2,3,4-tetrakis[2-(4,4'-cyanobiphenylyloxycarbonylphenylene-4-dimethylsily
lene)ethyl]-1,2,3,4-tetramethylcyclotetrasiloxane; phases: T.sub.G 52
s.sub.c 214 s.sub.A 214-228 I.
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